Character Sets (1.3.d)
A character set is basically a way of expressing text (letters, numbers, and symbols) as binary. In the 1960s, computers all used different character sets, so it was hard to make them communicate. Manufacturers realised this was a problem, so they had a meeting in America, and a set of codes called ASCII (American Standard Code for Information Interchange - pronounced ass-key). ASCII uses 8 bit to stand for each character - this is why a byte is normally made from 8-bits.
ASCII isn't the only character set - there are others, such as EBCDIC, which was used on IBM machines, and is based on BCD, and UNICODE, which is similar to ASCII, but represents far more characters, including Arabic, Chinese, and Japanese characters.